Effect of a semi-rigid backpack type thoracolumbar orthosis on thoracic kyphosis angle and muscle performance in older adults with hyperkyphosis: a randomized controlled trial

Abstract

Purpose

To investigate the effect of a semi-rigid backpack type thoracolumbar orthosis (TLO) on thoracic kyphosis angle (TKA) and potentially contributing factors of hyperkyphosis, including position sense and back muscle strength and endurance.

Method

This randomized, controlled trial was conducted on 48 older adults with hyperkyphosis, randomly allocated to an experimental or control group. The experimental group wore a semi-rigid TLO for 3 consecutive months. The control group received no external support or exercise. Thoracic kyphosis angle (TKA), joint position sense, back muscle strength and endurance were evaluated at the baseline and at the end of week 6 and week 12.

Results

The two-way (group × time) interactions were significant in terms of TKA (F = 37.88, p ≤ 0.001, η_p² = 0.45), muscle strength (F = 26.005, p ≤ 0.001, η_p² = 0.36), muscle endurance measured via load cell (F = 3.417, p = 0.039, η_p² = 0.06), and endurance holding time of Ito test (F = 3.629, p = 0.045, η_p² = 0.07). A further analysis using one-way repeated measures of ANOVA showed that TKA, muscle strength and endurance were significantly improved in the experimental group. Also, two-way interactions were significant for absolute error and variable error of trunk neutral repositioning test from a trunk flexed and/or extended position for global components and horizontal components trunk repositioning test.

Conclusion

Wearing a semi-rigid backpack type TLO even from an unknown brand for short periods during the day (e.g., 2–4 h) over 3 months not only modifies kyphotic posture but also can enhance back muscle performance in older adults with hyperkyphosis.

IMPLICATIONS FOR REHABILITATION

• Prescription of a semi-rigid backpack type thoracolumbar orthosis for older adults has no adverse effects such as muscle weakness if it is applied for short periods during the day.

• A semi-rigid backpack thoracolumbar orthosis can prevent position sense degradation in older adults with hyperkyphosis.

• A semi-rigid backpack type thoracolumbar orthosis may counteract trunk flexion and kyphotic posture by applying the biomechanical principles of the three-point pressure system.

• Improvement in spinal alignment resulting from wearing thoracolumbar orthosis should not occur in exchange for muscle deconditioning.

Keywords:

• Hyperkyphosis
• postural deformity
• spinal orthosis
• back muscles
• muscle strength
• proprioception
• position sense

Acknowledgments

The authors would like to thank all participants for their valuable contributions.

Ethical approval

The study protocol was approved by the Research Ethics Committee at Iran University of Medical Sciences (IR.IUMS.REC.1398.435) and followed the principles of the Declaration of Helsinki. All participants signed a written consent before enrollment.

Trial registration

The trial was registered in the Iranian Registry of Clinical Trials (www.irct.ir) on 6th April 2020 as IRCT20190811044505N1.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors would like to thank the Iran University of Medical Sciences for the partial financial support of this study [grant number: 15236].